Currently, large radial reactors have been widely used. For consideration of structure and process, such a reactor in scale-up usually has its catalyst bed divided into multi stages and separately placed into a same shell. Each stage has separation space formed therebetween, and reaction mass passes through a gas-collection channel of a catalyst bed along a radial direction, and moves downward along an axial direction, then passes through the separation space into a gas-distribution channel of a catalyst bed at a next stage. In the case of an exothermic reaction, typically, a heat transfer means is disposed in the separation space, such as a heat exchanger or a quench-fluid introducing means. Such multi-stage design provides a good solution for the demands of structure and process in scale-up of a reactor, however, when adopting a multi-bed-layer design, this approach faces the following problems: axial multi-stage technology leads to unrepeatable overlay of catalyst beds due to catalyst bed installation sequence, therefore it is unable to meet the requirements of further scale-up production; in applications of a multi-bed-layer radial reactor, because of its inability to adopt a multi-stage design, it usually has a cooling tube with/without an opening buried in the catalyst layers, so as to transfer reaction heat with coolant or quench fluid, but it destroys adiabatic conditions of the catalyst layers. The presence of cooling tube and quench fluid makes flow field and temperature distribution become very complex, causing a significant adverse effect on catalytic activity and lifespan; moreover, the regulation and control of coolant or quench fluid is very difficult.
The prior art presents a dizzying array of radial reactor arrangements. However, careful consideration of these arrangements, as one skilled in the art would do, allows a designer to understand limitations of unwarranted applications for features of one radial reactor to another, where either process, mechanical or structural requirements of a specific application create such practical obstacles.
U.S. Pat. No. 5,427,760 describes a rather subtle improvement for sequentially separate single bed radial reactors—addition of an external heat sink by way of a heat exchanger was an inventive step.
U.S. Pat. No. 1,970,923 describes a cylindrical reactor with only axial gas flow through multiple catalyst beds for product of sulfur trioxide, where a quench space above the catalyst bed is bounded by a perforated plate intended for gas re-distribution and direct gas quench within the space. The arrangement is especially ineffective, in that inadequate turbulent flow is achieved to achieve radial uniformity in temperature or quench gas mixing.
U.S. Pat. No. 4,880,603 describes an axial radial reactor for ammonia synthesis in which gas flow passes radially through only a single catalyst bed before flowing through narrow annular space to a subsequent catalyst bed. This design similarly is disabled as to uniformity of gas composition and temperature across a horizontal cross section thereof, as there is insufficient space for such uniformity to develop.
U.S. Pat. No. 2,450,804 describes an axial radial reactor having a single level of radial flow path from a center pipe to an outer annular collection space. In that radial flow path are three annularly sequential catalyst beds, spaced narrowly apart by perforated cylinders which allow injection of quench gas. The disability of this design is apparent to one skilled in the art, in that the spaced apart pipes used for injection of quench gas create cooled vertical zones separated by hot vertical zones due to inadequate mixing of gas from one reactor flowing immediately and without adequate mixing straight into the next catalyst bed.
U.S. Pat. No. 2,517,525 discloses a design similar to that of the '804 patent, in that it is not capable of having additional radial flow catalyst beds added above or below the single level of radial flow catalyst beds. However, the '525 patent provides for gas leaving one annular catalyst bed to flow upward to a very small space beneath a top hemispherical shell to mix with quenching gas. This design still suffers the disability of failing to provide adequate space volume in which uniform compositions and temperatures of the gas in horizontal cross section may be achieved before the gas flows to the next radial catalyst bed.
Therefore, there is an immediate need to provide a multi-bed-layer reactor, to solve the technical problems of a radial multi-bed-layer reactor, such as difficult-to-scale-up, complex pipelines in existing apparatus, unstable-at-work, difficult-to-operate, and hard-to-meet-processing-requirements, etc.